1. Field of Invention
This invention pertains to overhead ladders. More particularly, this invention pertains to a force-dampening system used in conjunction with an sectional overhead ladder such that when the ladder is collapsed, the force-dampening system limits the free extension of the ladder and when the ladder is extended, the force-dampening system assists with the collapse of the ladder.
2. Description of the Related Art
Overhead ladders are commonly used to provide convenient, temporary access to attics of houses or other structures without the loss of floor space occupied by a permanent stairwell. Typically, overhead ladders include a plurality of sections that are folded upon one another within a frame secured to a structure. The ladder typically includes hinges for connecting the sections. The sections of the ladder align during use to form a continuous ladder structure spanning from one surface to another.
An overhead ladder is typically accessible from beneath by way of a hatch mounted in the ceiling. Most commonly, a user must access such an overhead ladder by pulling down the ceiling-mounted hatch and manually extending the sections of the ladder. However, the sections of an overhead ladder are often heavy and cumbersome, and a user manually extending an extendable ladder faces a risk of injury caused by the sudden extension of the ladder due to the force of gravity acting on the ladder sections. FIG. 2 illustrates a typical overhead attic ladder constructed for being folded prior to storage. In this figure, it is more clearly illustrated that the various ladder sections are capable of free extension about their hinged joints.
Several devices have been developed to overcome these and similar problems associated with temporary ladders and other similar devices. Typical of the art are those devices disclosed in the following U.S. Patents:
Patent No.Inventor(s)Issue Date1,811,708F. E. BesslerOct. 27, 19286,354,682Bruce E. Nott, et alMar. 12, 2002
Of these patents, U.S. Pat. No. 1,811,708 (the '708 patent) discloses a foldable attic ladder that utilizes an electric motor to lower and raise the ladder. The '708 patent discloses a hinged panel capable of connecting to a ceiling, a foldable stair structure, and an electric motor. The foldable stair structure includes one section mounted on top of the panel and two folding sections hinged together and to the first section. The panel and the sections of the foldable stair structure are held by a plurality of supporting members. The supporting arms and the electric motor are connected to a rotating shaft in such a manner that when the electric motor is engaged, the rotating shaft actuates the supporting members which in turn lower the panel and extend the foldable stair structure.
U.S. Pat. No. 6,354,682, (the '682 patent) issued to Bruce E. Nott, et al., discloses an overhead storage device. The '682 patent discloses a storage container pivotally connected to a frame adapted to be connected to an overhead surface. A motorized actuator is connected to the storage container and is capable of controllably pivoting the storage container relative to the frame such that the reference plane moves between a generally horizontal position and a generally vertical position.